diff --git a/arrays_strings/reverse_words/__init__.py b/arrays_strings/reverse_words/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/arrays_strings/reverse_words/reverse_words_challenge.ipynb b/arrays_strings/reverse_words/reverse_words_challenge.ipynb
new file mode 100644
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+++ b/arrays_strings/reverse_words/reverse_words_challenge.ipynb
@@ -0,0 +1,155 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "<small> <i> This notebook was prepared by Marco Guajardo. For license visit [github](https://github.com/donnemartin/interactive-coding-challenges) </i> </small>\n",
+    "."
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Challenge Notebook\n"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Problem: Given a string of words, return a string with the words in reverse"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "* [Constraits](#Constraint)\n",
+    "* [Test Cases](#Test-Cases)\n",
+    "* [Algorithm](#Algorithm)\n",
+    "* [Code](#Code)\n",
+    "* [Unit Test](#Unit-Test)\n",
+    "* [Solution Notebook](#Solution-Notebook)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Constraints\n",
+    "* Can we assume the string is ASCII?\n",
+    "  * Yes\n",
+    "* Is whitespace important?\n",
+    "  * no the whitespace does not change\n",
+    "* Is this case sensitive?\n",
+    "  * yes\n",
+    "* What if the string is empty?\n",
+    "  * return None\n",
+    "* Is the order of words important?\n",
+    "  * yes\n"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Test Cases\n",
+    "* Empty string -> None\n",
+    "* \"the sun is very hot\" -> \"eht nus si yrev toh\"\n"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Algorithm\n",
+    "* Refer to the [Solution](https://github.com/donnemartin/interactive-coding-challenges/blob/master/arrays_strings/reverse_words/reverse_words_solution.ipynb) if you are stuck and need a hint, the solution notebook's algorithm discussion might be a good place to start."
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Code "
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 21,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [],
+   "source": [
+    "def reverse_words (S):\n",
+    "    #TODO: implement me\n",
+    "    pass "
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Unit Test\n",
+    "<b> The following unit test is expected to fail until you solve challenge </b>"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [],
+   "source": [
+    "from nose.tools import assert_equal\n",
+    "\n",
+    "class UnitTest (object):\n",
+    "    def testReverseWords(self):\n",
+    "            assert_equal(func('the sun is hot'), 'eht nus si toh')\n",
+    "            assert_equal(func(''), None)\n",
+    "            assert_equal(func('123 456 789'), '321 654 987')\n",
+    "            assert_equal(func('magic'), 'cigam')\n",
+    "            print('Success: reverse_words')\n",
+    "            \n",
+    "def main():\n",
+    "    test = UnitTest()\n",
+    "    test.testReverseWords()\n",
+    "\n",
+    "if __name__==\"__main__\":\n",
+    "  main()"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Solution Notebook\n",
+    "* Review the [Solution Notebook](https://github.com/donnemartin/interactive-coding-challenges/blob/master/arrays_strings/reverse_words/reverse_words_solution.ipynb) for discussion on algorithms and code solutions."
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.6"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/arrays_strings/reverse_words/reverse_words_solution.ipynb b/arrays_strings/reverse_words/reverse_words_solution.ipynb
new file mode 100644
index 0000000..e7942a1
--- /dev/null
+++ b/arrays_strings/reverse_words/reverse_words_solution.ipynb
@@ -0,0 +1,162 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "<small> <i> This notebook was prepared by Marco Guajardo. For license visit [github](https://github.com/donnemartin/interactive-coding-challenges) </i> </small>"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Solution notebook\n",
+    "## Problem: Given a string of words, return a string with the words in reverse"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "* [Constraits](#Constraint)\n",
+    "* [Test Cases](#Test-Cases)\n",
+    "* [Algorithm](#Algorithm)\n",
+    "* [Code](#Code)\n",
+    "* [Unit Test](#Unit-Test)\n",
+    "* [Solution Notebook](#Solution-Notebook)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Constraints\n",
+    "* Can we assume the string is ASCII?\n",
+    "  * Yes\n",
+    "* Is whitespace important?\n",
+    "  * no the whitespace does not change\n",
+    "* Is this case sensitive?\n",
+    "  * yes\n",
+    "* What if the string is empty?\n",
+    "  * return None\n",
+    "* Is the order of words important?\n",
+    "  * yes\n",
+    "\n"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Algorithm: Split words into a list and reverse each word individually\n",
+    "Steps:\n",
+    "\n",
+    "* Check if string is empty\n",
+    "* If not empty, split the string into a list of words \n",
+    "* For each word on the list\n",
+    "  * reverse the word\n",
+    "* Return the string representation of the list\n",
+    "\n",
+    "Complexity:\n",
+    "\n",
+    "* Time complexity is O(n) where n is the number of chars.\n",
+    "* Space complexity is O(n) where n is the number of chars. "
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [],
+   "source": [
+    "def reverse_words(S):\n",
+    "    if len(S) is 0:\n",
+    "        return None\n",
+    "    \n",
+    "    words = S.split()\n",
+    "    for i in range (len(words)):\n",
+    "        words[i] = words[i][::-1]\n",
+    "        \n",
+    "    return \" \".join(words)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 4,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Overwriting reverse_words_solution.py\n"
+     ]
+    }
+   ],
+   "source": [
+    "%%writefile reverse_words_solution.py\n",
+    "from nose.tools import assert_equal\n",
+    "\n",
+    "class UnitTest (object):\n",
+    "    def testReverseWords(self, func):\n",
+    "            assert_equal(func('the sun is hot'), 'eht nus si toh')\n",
+    "            assert_equal(func(''), None)\n",
+    "            assert_equal(func('123 456 789'), '321 654 987')\n",
+    "            assert_equal(func('magic'), 'cigam')\n",
+    "            print('Success: reverse_words')\n",
+    "            \n",
+    "def main():\n",
+    "    test = UnitTest()\n",
+    "    test.testReverseWords(reverse_words)\n",
+    "\n",
+    "if __name__==\"__main__\":\n",
+    "  main()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 5,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Success: reverse_words\n"
+     ]
+    }
+   ],
+   "source": [
+    "run -i reverse_words_solution.py"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.6"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/arrays_strings/reverse_words/reverse_words_solution.py b/arrays_strings/reverse_words/reverse_words_solution.py
new file mode 100644
index 0000000..1e44114
--- /dev/null
+++ b/arrays_strings/reverse_words/reverse_words_solution.py
@@ -0,0 +1,16 @@
+from nose.tools import assert_equal
+
+class UnitTest (object):
+    def testReverseWords(self, func):
+            assert_equal(func('the sun is hot'), 'eht nus si toh')
+            assert_equal(func(''), None)
+            assert_equal(func('123 456 789'), '321 654 987')
+            assert_equal(func('magic'), 'cigam')
+            print('Success: reverse_words')
+            
+def main():
+    test = UnitTest()
+    test.testReverseWords(reverse_words)
+
+if __name__=="__main__":
+  main()
\ No newline at end of file